1
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Kim J, Mayorga-Burrezo P, Song SJ, Mayorga-Martinez CC, Medina-Sánchez M, Pané S, Pumera M. Advanced materials for micro/nanorobotics. Chem Soc Rev 2024. [PMID: 39139002 DOI: 10.1039/d3cs00777d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
Autonomous micro/nanorobots capable of performing programmed missions are at the forefront of next-generation micromachinery. These small robotic systems are predominantly constructed using functional components sourced from micro- and nanoscale materials; therefore, combining them with various advanced materials represents a pivotal direction toward achieving a higher level of intelligence and multifunctionality. This review provides a comprehensive overview of advanced materials for innovative micro/nanorobotics, focusing on the five families of materials that have witnessed the most rapid advancements over the last decade: two-dimensional materials, metal-organic frameworks, semiconductors, polymers, and biological cells. Their unique physicochemical, mechanical, optical, and biological properties have been integrated into micro/nanorobots to achieve greater maneuverability, programmability, intelligence, and multifunctionality in collective behaviors. The design and fabrication methods for hybrid robotic systems are discussed based on the material categories. In addition, their promising potential for powering motion and/or (multi-)functionality is described and the fundamental principles underlying them are explained. Finally, their extensive use in a variety of applications, including environmental remediation, (bio)sensing, therapeutics, etc., and remaining challenges and perspectives for future research are discussed.
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Affiliation(s)
- Jeonghyo Kim
- Advanced Nanorobots & Multiscale Robotics Laboratory, Faculty of Electrical Engineering and Computer Science, VSB - Technical University of Ostrava, 17. listopadu 2172/15, Ostrava 70800, Czech Republic.
| | - Paula Mayorga-Burrezo
- Future Energy and Innovation Laboratory, Central European Institute of Technology, Brno University of Technology, Purkyňova 123, Brno 61200, Czech Republic
| | - Su-Jin Song
- Advanced Nanorobots & Multiscale Robotics Laboratory, Faculty of Electrical Engineering and Computer Science, VSB - Technical University of Ostrava, 17. listopadu 2172/15, Ostrava 70800, Czech Republic.
| | - Carmen C Mayorga-Martinez
- Advanced Nanorobots & Multiscale Robotics Laboratory, Faculty of Electrical Engineering and Computer Science, VSB - Technical University of Ostrava, 17. listopadu 2172/15, Ostrava 70800, Czech Republic.
| | - Mariana Medina-Sánchez
- CIC nanoGUNE BRTA, Tolosa Hiribidea 76, San Sebastián, 20018, Spain
- IKERBASQUE, Basque Foundation for Science, Plaza Euskadi, 5, Bilbao, 48009, Spain
- Micro- and NanoBiomedical Engineering Group (MNBE), Institute for Emerging Electronic Technologies, Leibniz Institute for Solid State and Materials Research (IFW), 01069, Dresden, Germany
- Chair of Micro- and Nano-Biosystems, Center for Molecular Bioengineering (B CUBE), Dresden University of Technology, 01062, Dresden, Germany
| | - Salvador Pané
- Multi-Scale Robotics Lab, Institute of Robotics and Intelligent Systems, ETH Zürich, Tannenstrasse 3, CH-8092 Zürich, Switzerland
| | - Martin Pumera
- Advanced Nanorobots & Multiscale Robotics Laboratory, Faculty of Electrical Engineering and Computer Science, VSB - Technical University of Ostrava, 17. listopadu 2172/15, Ostrava 70800, Czech Republic.
- Future Energy and Innovation Laboratory, Central European Institute of Technology, Brno University of Technology, Purkyňova 123, Brno 61200, Czech Republic
- Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
- Department of Medical Research, China Medical University Hospital, China Medical University, No. 91 Hsueh-Shih Road, Taichung, Taiwan
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2
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Heckel S, Wittmann M, Reid M, Villa K, Simmchen J. An Account on BiVO 4 as Photocatalytic Active Matter. ACCOUNTS OF MATERIALS RESEARCH 2024; 5:400-412. [PMID: 38694187 PMCID: PMC11059100 DOI: 10.1021/accountsmr.3c00021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 11/24/2023] [Accepted: 12/25/2023] [Indexed: 05/04/2024]
Abstract
Photocatalytic materials are gaining popularity and research investment for developing light-driven micromotors. While most of the early work used highly stable TiO2 as a material to construct micromotors, mostly in combination with noble metals, other semiconductors offer a wider range of properties, including independence from high-energy UV light. This review focuses on our work with BiVO4 which has shown promise due to its small band gap and resulting ability to absorb blue light. Additionally, this salt's well-defined crystal structures lead to exploitable charge separation on different crystal facets, providing sufficient asymmetry to cause active propulsion. These properties have given rise to fascinating physical and chemical behaviors that show how rich and variable active matter can become. Here, we present the synthesis of different BiVO4 microparticles and their material properties that make them excellent candidates as active micromotors. A critical factor in understanding inherently asymmetric micromotors is knowledge of their flow fields. However, due to their small size and the need to use even smaller tracer particles to avoid perturbing the flow field, measuring flow fields at the microscale is a difficult task. We also present these first results, which allow us to demonstrate the correlation between chemical reactivity and the flow generated, leading to active motion. Due to the nontoxic nature of BiVO4, these visible-light-responsive microswimmers have been used to study the first steps toward applications, even in sensitive areas such as food technology. Although these initial tests are far from being realized, we have to face the fact that a single microswimmer will not be able to perform macroscale tasks. Therefore, we present the reader with the first simple studies of collective motion, hoping for many new contributions to the field. The one-step synthesis of BiVO4 clearly paves the way for studies requiring large numbers of particles. We predict that the combination of promising applications for a nontoxic material which is readily synthesized in large quantities will contribute pivotally to advance the field of active matter beyond the proof-of-concept stage.
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Affiliation(s)
- Sandra Heckel
- Physical
Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
| | - Martin Wittmann
- Physical
Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
| | - Marc Reid
- Department
of Pure and Applied Chemistry, University
of Strathclyde, 295 Cathedral
Street, Glasgow G1 1XL, United Kingdom
| | - Katherine Villa
- Institute
of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans, 16, 43007 Tarragona, Spain
| | - Juliane Simmchen
- Physical
Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
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3
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Archer RJ, Ebbens SJ. Symmetrical Catalytic Colloids Display Janus-Like Active Brownian Particle Motion. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303154. [PMID: 37870200 PMCID: PMC10667803 DOI: 10.1002/advs.202303154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 08/30/2023] [Indexed: 10/24/2023]
Abstract
Catalytic Janus colloids, with one hemi-sphere covered by a hydrogen peroxide reduction catalyst such as platinum, represent one of the most experimentally explored examples of self-motile active colloid systems. This paper comparatively investigates the motile behavior of symmetrical catalytic colloids produced by a solution-based metal salt reduction process. Despite the significant differences in the distribution of catalytic activity, this study finds that the motion produced by symmetrical colloids is equivalent to that previously reported for Janus colloids. It also shows that introducing a Janus structure to the symmetrical colloids via masking does not significantly modify their motion. These findings could indicate that very subtle variations in surface reactivity can be sufficient to produce Janus-like active Brownian particle-type motion, or that a symmetry-breaking phenomena is present. The study will consequently motivate fresh theoretical attention and also demonstrate a straightforward route to access large quantities of motile active colloids, which are expected to show subtly different phenomenology compared to those with Janus structures.
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Affiliation(s)
- Richard J. Archer
- Molecular Robotics LaboratoryDepartment of RoboticsGraduate School of EngineeringTohoku UniversitySendai980‐8579Japan
| | - Stephen J. Ebbens
- Department of Chemical and Biological EngineeringUniversity of SheffieldMappin StreetSheffieldS1 3JDUK
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4
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Sharan P, Daddi-Moussa-Ider A, Agudo-Canalejo J, Golestanian R, Simmchen J. Pair Interaction between Two Catalytically Active Colloids. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300817. [PMID: 37165719 DOI: 10.1002/smll.202300817] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/16/2023] [Indexed: 05/12/2023]
Abstract
Due to the intrinsically complex non-equilibrium behavior of the constituents of active matter systems, a comprehensive understanding of their collective properties is a challenge that requires systematic bottom-up characterization of the individual components and their interactions. For self-propelled particles, intrinsic complexity stems from the fact that the polar nature of the colloids necessitates that the interactions depend on positions and orientations of the particles, leading to a 2d - 1 dimensional configuration space for each particle, in d dimensions. Moreover, the interactions between such non-equilibrium colloids are generically non-reciprocal, which makes the characterization even more complex. Therefore, derivation of generic rules that enable us to predict the outcomes of individual encounters as well as the ensuing collective behavior will be an important step forward. While significant advances have been made on the theoretical front, such systematic experimental characterizations using simple artificial systems with measurable parameters are scarce. Here, two different contrasting types of colloidal microswimmers are studied, which move in opposite directions and show distinctly different interactions. To facilitate the extraction of parameters, an experimental platform is introduced in which these parameters are confined on a 1D track. Furthermore, a theoretical model for interparticle interactions near a substrate is developed, including both phoretic and hydrodynamic effects, which reproduces their behavior. For subsequent validation, the degrees of freedom are increased to 2D motion and resulting trajectories are predicted, finding remarkable agreement. These results may prove useful in characterizing the overall alignment behavior of interacting self-propelling active swimmer and may find direct applications in guiding the design of active-matter systems involving phoretic and hydrodynamic interactions.
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Affiliation(s)
- Priyanka Sharan
- Chair of Physical Chemistry, TU Dresden, 01062, Dresden, Germany
| | | | - Jaime Agudo-Canalejo
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077, Göttingen, Germany
| | - Ramin Golestanian
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077, Göttingen, Germany
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford, OX1 3PU, UK
| | - Juliane Simmchen
- Chair of Physical Chemistry, TU Dresden, 01062, Dresden, Germany
- Pure and applied chemistry, University of Strathclyde, G11XL, Glasgow
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5
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Yuan X, Ferrer-Campos R, Garcés-Pineda FA, Villa K. Molecular Imprinted BiVO 4 Microswimmers for Selective Target Recognition and Removal. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2207303. [PMID: 36703511 DOI: 10.1002/smll.202207303] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/06/2023] [Indexed: 05/11/2023]
Abstract
Analogous to photosynthetic systems, photoactive semiconductor-based micro/nanoswimmers display biomimetic features that enable unique light harvesting and energy conversion functions and interactions with their surroundings. However, these artificial swimmers are usually non-selective and provide ineffective target recognition, resulting in poor surface analyte binding that affects the overall reactivity and motion efficiency. Here, the surface engineering of light-driven BiVO4 microswimmers by molecular imprinting polymerization is presented. After embedding surface recognition sites, the modified microswimmers can self-propel in a solution of a target molecule, without requiring toxic fuels, and degrade the target selectively in a pollutant mixture. These findings show that optimizing the design of semiconductor-based microswimmers with specific target recognition cavities on their surface is a promising strategy to achieve selective capture and degradation of organic pollutants, which is otherwise impossible because of the non-selective behavior of photogenerated reactive radicals. Moreover, this study provides a unique strategy to enhance the motion capabilities of single-component photocatalytic microswimmers in a specific chemical environment.
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Affiliation(s)
- Xiaojiao Yuan
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans, 16, Tarragona, E-43007, Spain
| | - Rebeca Ferrer-Campos
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans, 16, Tarragona, E-43007, Spain
| | - Felipe A Garcés-Pineda
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans, 16, Tarragona, E-43007, Spain
| | - Katherine Villa
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans, 16, Tarragona, E-43007, Spain
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6
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Mayorga-Burrezo P, Mayorga-Martinez CC, Pumera M. Photocatalysis dramatically influences motion of magnetic microrobots: Application to removal of microplastics and dyes. J Colloid Interface Sci 2023; 643:447-454. [PMID: 37086534 DOI: 10.1016/j.jcis.2023.04.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/30/2023] [Accepted: 04/04/2023] [Indexed: 04/24/2023]
Abstract
Micromachines gain momentum in the applications for environmental remediation. Magnetic components have been used to functionalize light-responsive micromachines to achieve efficient magnetic microrobots with photodegradation activity for decomposition of environmental pollutants. However, the influence of photocatalyst itself on the trajectory of micromotors in conjunction with magnetic motion was never considered. In this work, light-powered catalysis and transversal rotating magnetic field have been independently and simultaneously applied over Fe3O4@BiVO4 microrobots to investigate the dynamics of their hybrid motion. Light exposure of microrobots results in the production of reactive oxygen species (ROS) which power the microrobots, in addition to magnetic powered motion, and have a strong influence on the magnetic trajectories, resulting in an unexpected alteration of the direction of the motion of the microrobots. We have subsequently applied such magnetic/light powered micromachines for removal of microplastics in cigarette filter residues, one of the major contributors to the microplastic pollution, and dyes via photocatalysis. Such dual orthogonal propulsion modes act independently on the motion of the micromachines; and they also bring additional functionality as photodegradation agents. Hence, the dual magnetic/photocatalytic microrobots shall find a variety of catalytic applications in different fields.
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Affiliation(s)
- Paula Mayorga-Burrezo
- Center for Advanced Functional Nanorobots, Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Carmen C Mayorga-Martinez
- Center for Advanced Functional Nanorobots, Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Martin Pumera
- Center for Advanced Functional Nanorobots, Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic; Faculty of Electrical Engineering and Computer Science, VSB - Technical University of Ostrava, 17. listopadu 2172/15, 70800 Ostrava, Czech Republic; Department of Medical Research, China Medical University Hospital, China Medical University, No. 91 Hsueh-Shih Road, Taichung 40402, Taiwan; Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea.
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7
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Wittmann M, Voigtmann M, Simmchen J. Active BiVO 4 Swimmers Propelled by Depletion Gradients Caused by Photodeposition. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206885. [PMID: 36683219 DOI: 10.1002/smll.202206885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/15/2022] [Indexed: 06/17/2023]
Abstract
Artificial active matter often self-propels by creating gradients of one or more species or quantities. For chemical swimmers, most frequently either O2 or H+ that are created in certain catalytic reactions are causing the interfacial flows which drive the self-propulsion. While the palette of reactions is extending constantly, especially toward more bio-compatible fuels, the depletion of species is often overlooked. Here, the photodeposition of metal species on BiVO4 micro swimmers is considered. During the photodeposition reaction, metal ions are removed from the solution creating a depleted region around the particle. The ability of this depletion to drive active motion of artificial micro swimmers, as well as the influences of different metal ions and counter ions on the motion are investigated and cross compared.
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Affiliation(s)
- Martin Wittmann
- Chair of Physical Chemistry, TU Dresden, 01069, Dresden, Germany
| | | | - Juliane Simmchen
- Chair of Physical Chemistry, TU Dresden, 01069, Dresden, Germany
- Pure and applied Chemistry, University of Strathclyde, Glasgow, G1 1BX, UK
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8
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Heckel S, Bilsing C, Wittmann M, Gemming T, Büttner L, Czarske J, Simmchen J. Beyond Janus Geometry: Characterization of Flow Fields around Nonspherical Photocatalytic Microswimmers. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105009. [PMID: 35839469 PMCID: PMC9403636 DOI: 10.1002/advs.202105009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 05/04/2022] [Indexed: 05/25/2023]
Abstract
Catalytic microswimmers that move by a phoretic mechanism in response to a self-induced chemical gradient are often obtained by the design of spherical janus microparticles, which suffer from multi-step fabrication and low yields. Approaches that circumvent laborious multi-step fabrication include the exploitation of the possibility of nonuniform catalytic activity along the surface of irregular particle shapes, local excitation or intrinsic asymmetry. Unfortunately, the effects on the generation of motion remain poorly understood. In this work, single crystalline BiVO4 microswimmers are presented that rely on a strict inherent asymmetry of charge-carrier distribution under illumination. The origin of the asymmetrical flow pattern is elucidated because of the high spatial resolution of measured flow fields around pinned BiVO4 colloids. As a result the flow from oxidative to reductive particle sides is confirmed. Distribution of oxidation and reduction reactions suggests a dominant self-electrophoretic motion mechanism with a source quadrupole as the origin of the induced flows. It is shown that the symmetry of the flow fields is broken by self-shadowing of the particles and synthetic surface defects that impact the photocatalytic activity of the microswimmers. The results demonstrate the complexity of symmetry breaking in nonspherical microswimmers and emphasize the role of self-shadowing for photocatalytic microswimmers. The findings are leading the way toward understanding of propulsion mechanisms of phoretic colloids of various shapes.
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Affiliation(s)
- Sandra Heckel
- TU DresdenChair of Physical ChemistryZellescher Weg 1901069DresdenGermany
| | - Clemens Bilsing
- TU DresdenLaboratory for Measurement and Sensor System TechniqueHelmholtzstraße 1801069DresdenGermany
| | - Martin Wittmann
- TU DresdenChair of Physical ChemistryZellescher Weg 1901069DresdenGermany
| | - Thomas Gemming
- Leibniz Institute for Solid State and Materials Research DresdenHelmholtzstraße 2001069DresdenGermany
| | - Lars Büttner
- TU DresdenLaboratory for Measurement and Sensor System TechniqueHelmholtzstraße 1801069DresdenGermany
- Competence Center Biomedical Computational Laser Systms (BIOLAS)Helmholtzstraße 1801069DresdenGermany
| | - Jürgen Czarske
- TU DresdenLaboratory for Measurement and Sensor System TechniqueHelmholtzstraße 1801069DresdenGermany
- Competence Center Biomedical Computational Laser Systms (BIOLAS)Helmholtzstraße 1801069DresdenGermany
| | - Juliane Simmchen
- TU DresdenChair of Physical ChemistryZellescher Weg 1901069DresdenGermany
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9
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Wittmann M, Heckel S, Wurl F, Xiao Z, Gemming T, Strassner T, Simmchen J. Microswimming by oxidation of dibenzylamine. Chem Commun (Camb) 2022; 58:4052-4055. [PMID: 35262114 DOI: 10.1039/d1cc06976d] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Chemiophoretic nano- and micromotors require a constant flow of product molecules to maintain a gradient that enables their propulsion. Apart from a smaller number of redox reactions that have been used, catalytic reactions are the main source of energy with the obvious benefit of making on-board fuel storage obsolete. However, the decomposition of H2O2 seems to strongly dominate the literature and although motion in H2O through water splitting is becoming more popular, so far only a few different reactions have been used for propulsion of photocatalytic microswimmers. Here, we investigate the possibility of extending the range of possible fuelling reactions to organic reactions with high significance in organic synthesis - the oxidation of amines to imines. Herein, motion of the microswimmers is analysed at different amine concentrations and light intensities. The findings thereof are correlated with the reaction products identified and quantified by gas chromatography (GC).
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Affiliation(s)
- Martin Wittmann
- Freigeist Group, Physical Chemistry TU Dresden, Zellescher Weg 19, Dresden 01062, Germany.
| | - Sandra Heckel
- Freigeist Group, Physical Chemistry TU Dresden, Zellescher Weg 19, Dresden 01062, Germany.
| | - Felix Wurl
- Physical Organic Chemistry, Technische Universität Dresden, Dresden 01069, Germany
| | - Zuyao Xiao
- Freigeist Group, Physical Chemistry TU Dresden, Zellescher Weg 19, Dresden 01062, Germany.
| | - Thomas Gemming
- Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstraße 20, Dresden 01069, Germany
| | - Thomas Strassner
- Physical Organic Chemistry, Technische Universität Dresden, Dresden 01069, Germany
| | - Juliane Simmchen
- Freigeist Group, Physical Chemistry TU Dresden, Zellescher Weg 19, Dresden 01062, Germany.
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10
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Liebchen B, Mukhopadhyay AK. Interactions in active colloids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:083002. [PMID: 34788232 DOI: 10.1088/1361-648x/ac3a86] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
The past two decades have seen a remarkable progress in the development of synthetic colloidal agents which are capable of creating directed motion in an unbiased environment at the microscale. These self-propelling particles are often praised for their enormous potential to self-organize into dynamic nonequilibrium structures such as living clusters, synchronized super-rotor structures or self-propelling molecules featuring a complexity which is rarely found outside of the living world. However, the precise mechanisms underlying the formation and dynamics of many of these structures are still barely understood, which is likely to hinge on the gaps in our understanding of how active colloids interact. In particular, besides showing comparatively short-ranged interactions which are well known from passive colloids (Van der Waals, electrostatic etc), active colloids show novel hydrodynamic interactions as well as phoretic and substrate-mediated 'osmotic' cross-interactions which hinge on the action of the phoretic field gradients which are induced by the colloids on other colloids in the system. The present article discusses the complexity and the intriguing properties of these interactions which in general are long-ranged, non-instantaneous, non-pairwise and non-reciprocal and which may serve as key ingredients for the design of future nonequilibrium colloidal materials. Besides providing a brief overview on the state of the art of our understanding of these interactions a key aim of this review is to emphasize open key questions and corresponding open challenges.
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Affiliation(s)
- Benno Liebchen
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Aritra K Mukhopadhyay
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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11
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Heidari M, Jakob F, Liebchen B, von Klitzing R. Non-monotonic speed-dependence of microswimmers on wall distance. SOFT MATTER 2021; 17:9428-9433. [PMID: 34610082 DOI: 10.1039/d1sm01277k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
While substrates naturally occur in most microswimmer experiments, their impact on the swimming performance is not well understood. In the present study, we functionalize substrates with polymer brushes of varying swelling properties, grafting densities and brush lengths to systematically modify and explore the substrate-swimmer interactions. Notably, the swimming speed does not monotonically change with brush thickness, but shows a distinct maximum at a certain intermediate thickness, which results from two counteracting factors: surface charge and surface roughness. The results show that the speed of thermophoretic microswimmers does not only depend on the particle properties but is also strongly influenced by the properties of the underlying substrate. This provides a route to control the speed of microswimmers via the underlying substrate, which could be applied in the future e.g. to design complex motility landscapes by patterning substrates with polymer brushes. It is expected that similar effects would occur for diffusio- and electrophoretic particles.
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Affiliation(s)
- Mojdeh Heidari
- Department of Physics, Soft Matter at Interfaces, TU Darmstadt, 64289 Darmstadt, Germany.
| | - Franziska Jakob
- Department of Physics, Soft Matter at Interfaces, TU Darmstadt, 64289 Darmstadt, Germany.
| | - Benno Liebchen
- Department of Physics, Soft Matter Theory, TU Darmstadt, 64289 Darmstadt, Germany
| | - Regine von Klitzing
- Department of Physics, Soft Matter at Interfaces, TU Darmstadt, 64289 Darmstadt, Germany.
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12
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Feuerstein L, Biermann CG, Xiao Z, Holm C, Simmchen J. Highly Efficient Active Colloids Driven by Galvanic Exchange Reactions. J Am Chem Soc 2021; 143:17015-17022. [PMID: 34523911 DOI: 10.1021/jacs.1c06400] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Micromotors are propelled by a variety of chemical reactions, with most of them being of catalytic nature. There are, however, systems based on redox reactions, which show clear benefits for efficiency. Here, we broaden the spectrum of suitable reactions to galvanic exchange processes, or an electrochemical replacement of a solid metal layer with dissolved ionic species of a more noble metal. We study the details of motility and the influence of different reaction parameters to conclude that these galvanophoretic processes circumvent several steps that lose efficiency in catalytic micromotors. Furthermore, we investigate the chemical process, the charge, and flow conditions that lead to this highly efficient new type of active motility. Toward a better understanding of the underlying processes, we propose an electrokinetic model that we numerically solve via finite elements.
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Affiliation(s)
- Linda Feuerstein
- Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
| | - Carl Georg Biermann
- Institute for Computational Physics (ICP), Allmandring 3, 70569 Stuttgart, Germany
| | - Zuyao Xiao
- Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
| | - Christian Holm
- Institute for Computational Physics (ICP), Allmandring 3, 70569 Stuttgart, Germany
| | - Juliane Simmchen
- Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany
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13
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Abstract
Active matter comprises self-driven units, such as bacteria and synthetic microswimmers, that can spontaneously form complex patterns and assemble into functional microdevices. These processes are possible thanks to the out-of-equilibrium nature of active-matter systems, fueled by a one-way free-energy flow from the environment into the system. Here, we take the next step in the evolution of active matter by realizing a two-way coupling between active particles and their environment, where active particles act back on the environment giving rise to the formation of superstructures. In experiments and simulations we observe that, under light-illumination, colloidal particles and their near-critical environment create mutually-coupled co-evolving structures. These structures unify in the form of active superstructures featuring a droplet shape and a colloidal engine inducing self-propulsion. We call them active droploids-a portmanteau of droplet and colloids. Our results provide a pathway to create active superstructures through environmental feedback.
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14
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Wang L, Borrelli M, Simmchen J. Self‐Asymmetric Yolk–Shell Photocatalytic ZnO Micromotors. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202100083] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Linlin Wang
- Physical Chemistry TU Dresden Zellescher Weg 19 01069 Dresden Germany
| | - Mino Borrelli
- Center for Advancing Electronics Dresden & Faculty of Chemistry and Food Chemistry TU Dresden Mommsenstrasse 4 01069 Dresden Germany
| | - Juliane Simmchen
- Physical Chemistry TU Dresden Zellescher Weg 19 01069 Dresden Germany
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15
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Abstract
Living systems use catalysis to achieve chemical transformations to comply with their needs in terms of energy and building blocks. The pH is a powerful means to regulate such processes, which also influences synthetic systems. In fact, the pH sensitivity of artificial photocatalysts, such as bismuth vanadate, bears the strong potential of flexibly influencing both the motion pattern and the speed of catalytic microswimmers, but it has rarely been investigated to date. In this work, we first present a comprehensive view of the motion behavior of differently shaped bismuth vanadate microswimmers, discuss influences, such as shape, pH, and conductivity of the solutions, and find that the motion pattern of the swimmers switches between upright and horizontal at their point of zero charge. We then apply an immobilizable hydroxypyrene derivative to our substrates to locally influence the pH of the solution by excited-state proton transfer. We find that the motion pattern of our swimmers is strongly influenced by this functionalization and a third motion mode, called tumbling, is introduced. Taking other effects, such as an increased surface roughness of the modified substrates, into account, we critically discuss possible future developments.
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16
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Möller N, Liebchen B, Palberg T. Shaping the gradients driving phoretic micro-swimmers: influence of swimming speed, budget of carbonic acid and environment. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:41. [PMID: 33759011 PMCID: PMC7987694 DOI: 10.1140/epje/s10189-021-00026-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/22/2021] [Indexed: 05/07/2023]
Abstract
pH gradient-driven modular micro-swimmers are investigated as a model for a large variety of quasi-two-dimensional chemi-phoretic self-propelled entities. Using three-channel micro-photometry, we obtain a precise large field mapping of pH at a spatial resolution of a few microns and a pH resolution of [Formula: see text] units for swimmers of different velocities propelling on two differently charged substrates. We model our results in terms of solutions of the three-dimensional advection-diffusion equation for a 1:1 electrolyte, i.e. carbonic acid, which is produced by ion exchange and consumed by equilibration with dissolved [Formula: see text]. We demonstrate the dependence of gradient shape and steepness on swimmer speed, diffusivity of chemicals, as well as the fuel budget. Moreover, we experimentally observe a subtle, but significant feedback of the swimmer's immediate environment in terms of a substrate charge-mediated solvent convection. We discuss our findings in view of different recent results from other micro-fluidic or active matter investigations. We anticipate that they are relevant for quantitative modelling and targeted applications of diffusio-phoretic flows in general and artificial micro-swimmers in particular.
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Affiliation(s)
- Nadir Möller
- Institute of Condensed Matter Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany.
- Max Planck Graduade Center, Institute of Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany.
| | - Benno Liebchen
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 8, 64289, Darmstadt, Germany
| | - Thomas Palberg
- Institute of Condensed Matter Physics, Johannes Gutenberg Universität, Staudinger Weg 7, 55128, Mainz, Germany
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17
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Fränzl M, Muiños-Landin S, Holubec V, Cichos F. Fully Steerable Symmetric Thermoplasmonic Microswimmers. ACS NANO 2021; 15:3434-3440. [PMID: 33556235 DOI: 10.1021/acsnano.0c10598] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A cornerstone of the directed motion of microscopic self-propelling particles is an asymmetric particle structure defining a polarity axis along which these tiny machines move. This structural asymmetry ties the orientational Brownian motion to the microswimmers directional motion, limiting their persistence and making the long time motion effectively diffusive. Here, we demonstrate a completely symmetric thermoplasmonic microswimmer, which is propelled by laser-induced self-thermophoresis. The propulsion direction is imprinted externally to the particle by the heating laser position. The orientational Brownian motion, thus, becomes irrelevant for the propulsion, allowing enhanced control over the particles dynamics with almost arbitrary steering capability. We characterize the particle motion in experiments and simulations and also theoretically. The analysis reveals additional noise appearing in these systems, which is conjectured to be relevant for biological systems. Our experimental results show that even very small particles can be precisely controlled, enabling more advanced applications of these micromachines.
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Affiliation(s)
- Martin Fränzl
- Peter Debye Institute for Soft Matter Physics, Molecular Nanophotonics Group, Universität Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
| | - Santiago Muiños-Landin
- Peter Debye Institute for Soft Matter Physics, Molecular Nanophotonics Group, Universität Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
- Smart Systems and Smart Manufacturing, Artificial Intelligence and Data Analytics Laboratory, Polígono Industrial de Cataboi, AIMEN Technology Centre, 36418 Pontevedra, Spain
| | - Viktor Holubec
- Theory of Condensed Matter, Institute for Theoretical Physics, Universität Leipzig, Brüderstr. 16, 04103 Leipzig, Germany
- Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague, Czech Republic
| | - Frank Cichos
- Peter Debye Institute for Soft Matter Physics, Molecular Nanophotonics Group, Universität Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
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